Optical fibers are normally constructed with a protective outer coating, which is frequently acrylate or another plastic material. The coating material is typically applied to the fiber during manufacture while the coating is still tacky. The coating may be subsequently cured by ultraviolet light to form the coated fiber. A jacket may be provided around one or more coated fibers for protection. Prior to splicing the optical fibers, the ends of two optical fibers to be spliced together needs to be stripped of their protective coating and cleaved to provide an accurately sheared end surface for mating.
Existing stripping devices include a tool as shown in U.S. Pat. No. 4,271,729 to Perrino et al. Such a tool and similar tools are sold by Klein Tools of Chicago, Ill. and Micro Electronics, Inc. of Newport, R.I. Tools of this type may include two elongated blade members 1, with each blade member 1 holding an elongated metal strip 2, details of which can be seen in FIGS. 1 and 2. Each metal strip 2 typically includes a semi-circular notch 3 with a beveled surface 4. The blade members 1 are moved together and apart in a direction perpendicular to the longitudinal axis of the coated fiber 5 by a pair of handles, not shown in FIGS. 1 and 2. When the handles are pivoted toward each other against a biasing force, the leading edge 6 of the beveled notches 3 forms a circle having a diameter the same as, or just slightly larger than, the diameter of the fiber 7. In operation, a coated fiber 5 is inserted into the tool and the handles are squeezed. This causes the leading edge 6 of the notches 3 to cut into the coated fiber 5 around the entire circumference. The coated fiber 5 is then pulled along the axis of the fiber, i.e., in the direction of arrow 8, into the beveled surface 4 of the notches 3 so that the beveled surface scrapes the coating 9 off of the fiber 7 in a fragmented manner as the fiber is being pulled against the beveled edge. U.S. Pat. No. 4,969,703 to Fyfe et al. shows a device similar to the tools disclosed in U.S. Pat. No. 4,271,729 mounted to a base with a movable fiber holding clamp.
However, these stripping tools and others that strip fibers using similar scraping methods have significant drawbacks. As the fiber is pulled through the beveled notched portions of the blades, their constant scraping of the coating tends to make the blade holders oscillate slightly. This can lead to the fiber becoming scratched. Other strippers operate on the theory of scraping and are also highly susceptible to scratching the fiber. Moreover, microscopic alignment and tolerancing errors can also cause the fiber to be scratched. This can be significant as one small scratch in the fiber can reduce its strength by up to 90%. Additionally, the hand-held stripping units as well as the stripper unit shown in U.S. Pat. No. 4,969,703 lack exceptional stability which could create misalignment between the fiber and the stripping blade and also cause scratching.
Attempts to solve these drawbacks have not been entirely successful. U.S. Pat. No. 5,033,335 to Yatsu et al. discloses the use of a heating element which applies direct heat to a clamped free end of the coated fiber. The heating element is intended to soften the coating. However, merely softening the coating does not solve the problem of scratching. Moreover, the combination of clamping the free end of the fiber and applying direct heat can damage the fiber. Additionally, the fact that the stripping blade surface does not extend entirely around the circumference of the coated fiber makes the stripping process less than optimal.
U.S. Pat. No. 4,971,418 to Dorsey et al. attempts to overcome these problems by stripping the coating off of the fibers by using a combination of an acid and a laser to melt away the coating. However, this process includes other drawbacks, including the generation of toxic waste, the exposure of potentially hazardous material to the operator, and it is a costly process. Accordingly, a solution that overcomes the drawbacks of the prior art was thus necessary.